Reenterent Chess

by Edward Lovett

RULES SUMMARY

Essentially, play is as per FIDE chess, although special
rules pertain to capturing. Main playing area is a board
comprising 5 x 8 squares; attached to this board is the
reenterent square, via which the most recently captured piece
has the possibility of reentering play. A special bishop move
is also available, which allows a bishop to switch to the
alternate coloured squares. As might be expected, pawns promote
upon reaching the eighth rank, and winning is accomplished by
checkmating the opponent.

PLAYING BOARD

Squares are alternately coloured dark and light. Initial
piece placement is as shown. Note the square to the right of
the main playing area; this is the reenterent square.

Click here for a photo of a prototype
playing board with initial piece placement (jpeg 12k).

PLAY

I. CAPTURING

On capturing an opponent's piece, the piece is placed on the
reenterent square by the player doing the capturing, displacing
a piece, if any, already on that square.

II. REENTERING A PIECE FROM THE REENTERENT SQUARE

A piece on the reenterent square may possibly 'escape' from
capture and return to battle according to the following rules.
Note that only the player who initially owned that piece may
possibly return it to play - that is, there are no defections
in this variant.

REENTERENT RULES

A piece on the reenterent square may be returned to play if:

1. It is that players turn to move.

2.
The player is not in check; if in check, a piece from the
reenterent square may only be reentered if it can block the
check (subject to rule 3 below). A reenterent piece cannot
capture a checking piece.

3. There is an 'appropriate
square' to return the piece to; all pieces attempting to escape
try to find their way back to base camp as a means of
orienting their way back into battle. An 'appropriate
square' is defined as the square it initially occupied at the
start of play, or a square it may have legally moved to on
its first move. There is an additional constraint in that
such a square must also be vacant.

A few
notes follow that may help clarify some points of play. Note
particularly rules for reentering a pawn.

III. REENTERING PIECES - Notes

Let Black capture White's knight; the white knight is placed
upon the reenterent square
by Black, concluding Black's move. Now, assuming
that White is not in check, White may return the knight to any of
d1 (the square it originally occupied) or to either c3 or e3,
squares to which a move is available to the white knight at the
start of play, provided the chosen square is vacant.

White is under no compulsion to return the piece to play.
He may have a forced mate, for instance, or a sound combination
that will return a piece of greater value. Of course, in this
latter instance, he will lose his knight as it will be displaced
from the reenterent square. If desired, and provided no
captures have taken place, the knight may be returned to play
at any time by White, subject to the reenterent rules
above.

Perhaps you are wondering if a piece may be returned to play,
and by virtue of the position, give 'check' at the same time:
happily, the answer is yes (all the more glory your return
to battle!). You may also block a check to your king, or
thwart mate, should the position present itself (provided
of course, rule 3 is not violated).

Note that the queen, bishop and rook may only be returned to
play on their original respective
squares, as they have no other legal move available to them at this
time. This implies that if any of these pieces are captured on
their original squares, or are captured elsewhere and any piece
is occupying their respective initial squares, then
they cannot be immediately returned to play; by virtue of this,
a player whose piece is so captured will be somewhat limited in
replying to other threats or combinations as any piece
they
capture, for example, a pawn, will displace
a piece already on the reenterent square,
say possibly their queen.

With one additional constraint, a pawn on the reenterent
square may also be returned to play provided the three
reenterent rules (above) are not violated; a pawn may only be
returned to an open file (that is, a file (column) that
does not already contain a pawn of the same colour). It need
not be the file from which it was captured. Note that,
theoretically, all pawns have at least three moves available
for reentry - the initial square occupied at start of
play, and the square one step or two steps forward from
this square, these squares being moves which are legally
available to the pawn at start of play.

Since a
pawn can reenter on any open file, it may possibly have
several 'starting squares' and forward moves from which to
choose. Pawns returned to an initial square (that is, on
rank 2) regain their initial (optional) two move step - we may
think of it as a consequence of the terrain, in that the
battlefield slopes down in this area and it is thus possible to
make more progress.

Let us consider one possible scenario: the pawn on b2 has
been captured on its original square and there are no other
pawns of the same colour on that file and the position is
quiescent. Further, an opponent's pawn is situated on b3.
Can the pawn captured on b2 (now sitting on the
reenterent square) be returned to play on b4?
Yes - pawns
may sneak by the enemy when reentering their own camp.
Any square that a pawn may have
initially occupied, or could have moved to from such a square,
provided it is vacant (and the file contains no
other pawn of that colour), is a
contender for reentry. Note that, depending on
positional factors, it may be desirous to reenter the
pawn captured on b2 to another open file.

For the record, a pawn reentered onto rank 2 and then (at
some time) proceeding to a 2 square forward move, may be
subjected to en passant capture.

IV. CASTLING

Castling is permitted and rather unique, and is not for the
faint-hearted. Castling exposes the king centrally, and the
rook practically crosses the back rank in the process. All FIDE
criteria for castling is assumed and will not be repeated here.

Think of this move as a special pathway through the camp that
the king may negotiate with an aide under the cover of darkness.
Rather than a 'move to safety' as in FIDE chess, this move
is more surprising in nature,
demonstrating more than anything the 'boldness' of the king
as he blatently enters the fray.

To formalise this procedure, the king moves from its initial
square to that of its bishop's initial square; the rook is then
moved to the queen's initial square, constituting a 'single
move', as per FIDE rules. Remember, all normal rules for
castling apply.

V. SPECIAL BISHOPS' MOVE

At the beginning of play, the players bishops are on the
alternate coloured squares; given the chance they will
happily glide around the board and 'never the twain shall
meet'. In 'usual' chess, if you only have one bishop,
that bishop can only ever exert control over half the
total squares. Not so in reenterent chess. Men of the
cloth (the bishops) knoweth of the ancient catacombs
beneath the squares c4 and c5 whereby they may switch to the
alternate coloured squares.

Any time a bishop moves to one of the squares c4 or c5,
it may
switch to the other square, if that square is vacant, as the
conclusion to its move. Whilst it immediately gets control
over these alternate coloured squares (that is, may
possibly give check, or threaten a piece) it cannot continue
moving until the opponent has moved.

Admittedly, this move is hard to make when the board is
crowded with pieces, but provides a measure of extra strength to
the bishop towards the endgame.

The special bishops' move is entirely optional, but if not
made immediately, requires a separate move to accomplish.
Thus, a bishop sitting on c5 may move to c4 in one
turn. A bishop moving to c5 may finish their move
on c4 (provided, in both instances, c4 is vacant).
Remember, no other piece knows of the catacombs; this
special move is only available to bishops.